The Heart Of The Matter: All You Wanted To Know About Heart Disease
The human heart is a marvel of nature. It beats almost 1 lakh times a day, pumping blood in the body with each beat of the heart. For its proper functioning, the heart muscle has to be healthy.
The heart gets its nutrition and oxygen through blood that is supplied by coronary arteries. The heart is divided into two parts, right and left. The right heart has two chambers, right atrium and right ventricle. Similarly left side heart has two chambers - left atrium and left ventricle. In all, there are four chambers in the heart. The right side of the heart receives impure blood from the body and pumps it into the lungs. Blood gets purified in the lungs and returns back to the left side of heart from where it is pumped back into the body. Four valves, two on left side (mitral and aortic) and two on the right side of the heart (pulmonary and tricuspid) act as one-way doors to direct blood flow.
The coronary arteries bring oxygen and nutrients to the heart muscle. They divide into smaller branches so that each part of the heart muscle receives nutrients. The left coronary artery feeds the left side and front of the heart muscle. The right coronary artery feeds the right side of the heart and has branches that extend to the back. Over the time, these arteries can get damaged and be influenced by the way you live. They can become narrowed or even blocked completely from years of smoking, high blood pressure, diabetes, high fat/cholesterol food, too little exercise and too much stress. The result is poor blood flow and in some cases, a heart attack. When there is partial or total block of these coronary arteries, it is known as coronary artery disease.
Coronary artery disease (CAD)
CAD occurs because of deposition of fats and cholesterol (which usually occurs when fats are high in blood but may occur even when fats are normal) and clotting of blood in the coronary arteries. The various reasons responsible are family history, increased fat intake in diet, diabetes, smoking, high blood pressure, lack of exercise, stress etc.
When the coronary arteries are partially blocked (>50% but <100%), the oxygen supply may be adequate at rest but on activity it falls short, as oxygen demand of heart increases with activity. Angina (symptom of a blocked artery) usually manifests as suffocation, pressure, heaviness or pain in centre of chest which then may go to neck, jaw, back and left arm. However, it can occur only in jaw, neck, arm or back. Some times it can only cause a sense of gas in upper abdomen, or breathlessness on activity. When angina occurs at slight activity or at rest, it is called unstable angina or pre-heart attack angina. If not treated in time, heart attack may occur in many of these patients.
When the blood supply is totally blocked suddenly by blood clot formation, it causes heart attack. This presents as severe prolonged angina not relieved by tablet Sorbitrate and usually associated with perspiration and sense of sinking or impending doom. However, it can also manifest just as vomiting, gas in upper abdomen, sudden onset of shortness of breath, dizziness or sweating. In some cases, (especially in diabetics) heart attack may be without any symptom, what is known as silent heart attack.
One must remember that sooner the treatment is begun, better are the chances of saving the heart muscle and patients life. Hence no time should be wasted. The patient should be on absolute rest, tablet Sorbitrate should be placed underneath the tongue and a tablet of Disprin should be given dissolved in water. Once the patient is in hospital, he is either given treatment to dissolve the clot (which has caused total block of coronary artery) by giving Streptokinase injection or where possible, angiography followed by opening of the clogged artery with a balloon (primary angioplasty).
Coronary angiography is a technique in which the coronary artery can be seen on specialised X-ray machine. It is a diagnostic method, and not a treatment by itself. It is done under local anaesthesia. The patient remains fully conscious and can see his angiography image on the monitor. Usually through the thigh arteries and sometimes through the arm, special tubes are introduced to the mouth of coronary arteries and a drug (dye) is injected which fills the coronary artery enabling the doctor to see any blocked areas. It is a safe procedure.
Balloon angioplasty and stenting - Balloon angioplasty is done exactly in the same way as coronary angiography. This is done under local anaesthesia. A special tube with a balloon at the tip, is placed at the site of narrowing in the coronary artery and the balloon is inflated. This results in widening of the coronary artery. Stents are metallic springs which are put after ballooning to prevent recoil/reclosure of the artery. There are 10-20% chances of narrowing again of an artery after ballooning plus stenting.
Coronary artery bypass graft surgery
CABG surgery is an open heart operation in which arteries or veins are taken from another part of the body to channel needed blood flow to the coronary arteries. The arteries or veins used in the operation are nonessential, removing them does not significantly affect the blood circulation of the part they are taken from.
The arteries used are on the inside of the chest along the side of the breast bone on the inner forearm and along the stomach. The vein that is typically used comes from just beneath the skin on the inside of the leg and thigh. Some times veins may be removed from the back of legs or arms. During surgery these arteries or veins are connected directly to the coronary arteries on the surface of the heart beyond the blockages. This way blood can flow through them to bypass the narrowed or closed points.
Coronary artery bypass operations are performed either by using a heart-lung machine or on the beating heart. A heart-lung machine makes it possible to stop the beating of the heart as it takes over the blood circulation through the body. Then the grafts can be precisely connected to the tiny coronary arteries. In the latter technique, the heart beat is not stopped. Instead an external stabiliser system is used to reduce the mobility of heart in the area the doctors are operating.